Stewart Audio CVA50-1 Priority PA User manual

Owner’s Manual
CVA50-1 PRIORITY PA
www.stewartaudio.com
April 2013

2
Important Safety Instructions
Before using your Stewart Audio Inc. Power Amplier, please read this
Owner’s Manual carefully to ensure optimum trouble-free perfor-
mance.
WARNING: TO REDUCE THE RISK OF ELECTRICAL SHOCK, DO NOT EX-
POSE THIS AMPLIFIER TO RAIN OR MOISTURE. DANGEROUS HIGH
VOLTAGES ARE PRESENT INSIDE THE ENCLOSURE. DO NOT OPEN THE
CABINET. REFER SERVICING TO QUALIFIED PERSONNEL ONLY.
The lighting bolt within arrowhead symbol, within an
equilateral triangle, is intended to alert the user to the
presence of un-insulated “dangerous voltage” within
the product’s enclosure that may be of sufcient mag-
nitude to constitute a risk of electrical shock to person.
The exclamation point within an equilateral triangle, is
intended to alert the user to the presence of important
operating and maintenance (servicing) instruction in the
literature accompanying the appliance.
Important Safety Instruction – Please Read Prior to Product
Installation.
1. Installation should be performed by a trained and licensed professional to
insure safe and lasting operation.
2. All of the safety and operating instructions should be read before the am-
plier is installed or operated. Retain these instructions for future refer-
ence. All instructions should be followed; all warnings on the amplier
and in the operating instructions should be adhered to.
3
3. The amplier should be situated so that its location and position does not
interfere with its proper ventilation. For example, the amplier must not
be placed on a rug, bed, sofa or similar surface that impedes airow
across the chassis. Airow around the unit should be unobstructed.
4. This amplier should not be used near water, for example, near a bathtub,
in a wet basement, near a swimming pool, etc. This amplier is intended
to be operated in a controlled indoor environment.
5. Do not place the amplier near heat sources such as radiators, heat regis-
ters, stoves, or other appliances that produce heat.
6. The amplier’s power supply should only be connected to 120 VAC, 60
Hz power source. Do not defeat the ground or polarization of the power
plug.
7. Route power cord and other cables so that they are not likely to be
walked on, tripped over or stressed. Pay particular attention to condition
of cords and cables at plugs and at the point where they exit the ampli-
er. To prevent risk of re or injury, damaged cords and cables should be
replaced immediately.
8. Clean the amplier with a clean, damp cloth. Do not use solvents or abra-
sive cleaners. Never pour any liquid on the amplier.
9. When left unused for a long period of time, the power cord should be
unplugged from the outlet.
10. Damaged Ampliers requiring service should be repaired by a qualied
service technician when:
a. The power cord or AC plug has been damaged.
b. Objects have fallen, or liquid has spilled into the unit.
c. The amplier has been exposed to rain or other moisture.
d. The amplier does not appear to operate normally or exhibits
a marked change in performance.
e. The amplier has been dropped or the enclosure
damaged.
11. The user should not attempt to service the amplier beyond that de-
scribed in the operating instructions. All other servicing should be referred
to qualied service personnel.

4
Table of Contents
Important Safety Instructions······························································2
Table of Contents················································································4
1 Welcome ·························································································5
1.1 Features··············································································· 5
1.2 Using this Manual································································5
2 Setup ·······························································································6
2.1 Setup Precautions ·······························································6
2.2 Amplier Installation ···························································· 6
2.2.1 Pole-Mount Installation··········································· 6
2.2.2 Universal-Mount Installation ···································7
2.2.3 Product Dimensions ··············································· 8
2.3 Proper Cooling Considerations ············································8
2.4 Input Connections ·······························································9
2.4.1 Balanced Input Connections···································9
2.4.2 Unbalanced Input Connections·····························10
2.4.3 RCA······································································· 11
2.4.4 Stereo ···································································12
2.4.5 PA Euro Block ·······················································12
2.5 Output Connections ·························································· 13
2.5.1 Constant Voltage ················································· 14
2.5.2 Wiring Example ···················································· 14
3 Operation ······················································································15
3.1 Operation Precautions ······················································· 15
3.2 Controls, Indicators, and Connectors ································16
3.2.1 Indicators ······························································ 17
3.2.2 Controls ································································17
3.2.3 Remote Volume Control ······································· 18
3.2.4 PA Ducking ··························································· 19
4 Troubleshooting···········································································20
5 Technical Specications······························································ 22
6 Warranty Information·································································· 23
6.1 Warranty Summary····························································23
6.1.1 Eligibility for Factory Repair ·································· 23
6.2 Return Procedure ······························································24
6.2.1 Return Authorization············································· 24
6.2.2 Packaging Instructions··········································24
6.2.3 Shipping Instructions ············································24
6.2.4 Estimate Approval·················································25
6.2.5 Payment of Non-Warranty Repair·························25
7 Accessories ···················································································26
5
1 Welcome
Congratulations on the purchase of your new Stewart Audio CVA50-1
Priority PA power amplier. This amplier has been designed and built
to provide you with years of high-quality audio performance and trouble
-free operation. If after reading this manual you should have any ques-
tions concerning amplier installation and operation, please contact
your Authorized Stewart Dealer, or you may contact us directly using
the contact information provided on the back of this manual.
1.1 Features
Your Stewart Audio CVA50-1 Priority PA amplier is the result of years
of experience in the design and manufacture of quality ampliers. As
such it provides a combination of performance and operational benets
that simply cannot be found in conventional ampliers.
 Sub Compact 1/3 rack package
 Constant voltage amplier (70.7V / 100V)
 Adjustable ducking of local inputs
 Microphone input with adjustable pre-gain
 Remote volume control
 External inline power supply
 Made in the USA
1.2 Using this Manual
In order to obtain maximum performance from your CVA50-1 Priority
PA Amplier, please take time to read this brief owner’s manual and
carefully follow the guidelines for connection and operation.
This manual provides you with the information necessary to safely in-
stall and operate your new CVA50-1 Priority PA amplier in the most
common scenarios. If you nd yourself requiring additional assistance,
please feel free to contact your Authorized Dealer, or you may contact
us directly using the contact information provided on the back of this
manual.

6
2 Setup
2.1 Setup Precautions
CAUTION: Before installing your amplier, make sure that
you have read the Important Safety Precautions at the be-
ginning of this manual.
2.2 Amplier Installation
The CVA50-1 Priority PA incorporates a number of different mounting
options in order to t your installation needs.
2.2.1 Pole-Mount Installation
The CVA50-1 Priority PA amplier casing has mount holes on both the
top as well as the side of the unit which can be used with the AV-Pole
bracket available from Stewart Audio. Two screws are included in the
kit which will afx the bracket to the top or side of the unit.
Part Number: AV-Pole
7
2.2.1 Universal-Mount Installation
The CVA50-1 Priority PA also has a universal bracket available which
allows the unit to be mounted against a wall or under a table. Two
screws are included in the kit which will afx the bracket to the top or
the side of the unit. Once this is done, two holes are available for
mounting the unit where desired.
CAUTION: Use only the screws provided in mounting
brackets to the amplier. Do not over-tighten.

8
2.2.3 Product Dimensions
2.3 Proper Cooling Considerations
Because CVA50-1 Priority PA ampliers regulates their temperature
using convection cooling and no fans, the ampliers must be given ade-
quate space to allow for proper airow. Do not stack the ampliers on
top of each other or mount it in a way that other equipment will block
airow along the surfaces of the case.
CAUTION: Inadequate airow to the amplier can cause the
amplier to overheat and potentially become damaged in
the process. Be sure to provide plenty of air space to allow
for convection cooling.
CVA50-1 PA
6.25in
15.9cm
1.38in
3.5cm
1.38in
3.5cm
4.13in
10.5cm
9
2.4 Input Connections
Your CVA50-1 Priority PA amplier is provided with a 3-pin Euro Block
connector for its input connection. This connector will accept both bal-
anced or unbalanced connections, however some modications must
be made for an unbalanced connection. See the next two sections for
instructions on connecting your amplier to its input source.
2.4.1 Balanced Input Connections
When using a balanced input source and connector, you must ensure
that the hot, cold, and ground pins of the connector are matched up to
the +, -, and ground pins of the CVA50-1 Priority PA Euro Block con-
nector respectively. Diagrams have been provided for standard XLR
and TRS connectors. Please refer to the manual of your input source in
case it does not follow the standard pin-out.
NOTE: The CVA50-1 Priority PA ampliers does not accept
TRS inputs wired for a stereo source. TRS inputs should
only be used for balanced mono inputs.

10
2.4.2 Unbalanced Input Connections
When using an unbalanced input source and connector, a jumper must
be added between the negative (-) terminals and the ground terminals.
Once this has been done, the unbalanced source can be connected to
the positive (+) and ground terminals. Please refer to the manual of
your input source in case it does not follow the standard pin-out. For
your convenience, pre-wired connectors are available for purchase, see
the next page for details.
NOTE: A jumper is required for connecting an unbalanced
input.
NOTE: The CVA50-1 Priority PA ampliers does not accept
stereo inputs. Either one side must be selected from the
stereo source or an overload-protected Y-cable must be
used to sum them to mono. It is highly recommended that
you purchase the pre-wired connectors mentioned on the
next page. Damage to source equipment can result from
11
Pre-wired unbalanced connectors are available for purchase from Stew-
art Audio. These will allow for a quicker installation with less room for
error when connecting the CVA50-1 Priority PA amplier to an unbal-
anced source. The summing adapters will properly sum a stereo source
for use with the mono input on the rear of the amplier without caus-
ing sound cancellation. Part numbers are found below the diagrams.
2.4.3 RCA Input
The rst input channel is a stereo RCA jack which is then summed to
mono before the nal output. Refer to the diagram below for wiring
directions.
ADPT-RCA
Mono
Female RCA
ADPT-SUMRCA
Stereo
Female RCA
ADPT-SUM35
Stereo
Female 3.5mm
+Ground
(Shield)
+/Right
+/Left
Shield
Right
Left

12
2.4.3 Stereo 3.5mm
The second input channel is a stereo RCA jack which is then summed
to mono before the nal output. Refer to the diagram below for wiring
directions.
2.4.4 25V PA Euro Block
The third input channel is a Euro Block connector which can be wired
to any unbalanced input. Should you be wiring up a stereo source, use
both the left and right pins of the connector. A mono source will only
require the use of the ground and left pins.
+/Left
-/Right
Ground
(Shield)
+/Left
-/Right
Ground
(Shield)
13
2.5 Output Connections
Because of the differences in the way that constant-voltage ampliers
work as opposed to a typical 8-ohm setup, the wiring procedure and
the gauge of wire used is very different.
Constant voltage systems and speakers use a smaller current ow than
the typical 8ohm systems and thus can use a higher gauge (thinner
diameter) wire. Please refer to the following chart to choose the appro-
priate wire gauge for your installation.
Speaker leads connect by means of removable Euro Block connectors
supplied with the unit. Strip speaker leads 1/4” and insert leads into
connector observing proper polarity. With a small, at-blade screwdriv-
er, tighten the screw until the leads are held securely in place. Inspect
for possible shorts or broken wires.
Distance Wire Gauge
Up to 500ft 22 AWG
500 to 1000 ft. 20 AWG
Over 1000ft 18 AWG

14
2.5.1 Constant Voltage
The Euro Block connector on the rear of the amplier is capable of sup-
plying output at 70V.
2.5.2 Wiring Example
The diagram below is a typical wiring setup for two speakers with out-
board step-down transformers wired in parallel to the 70V output op-
tion of a CVA50-1 Priority PA amplier.
15
3 Operation
3.1 Operating Precautions
1. Before use, your amplier must be congured for proper opera-
tion, including input and output wiring hookup. Improper wiring
can result in damage to equipment or potentially harm to the
operator. Consult section 2 for setup instructions.
2. Tampering with the circuitry, or making unauthorized changes
is not only dangerous but may also violate local regulations.
3. Use care when making connections between the amplier and
the input or output equipment. Using equipment that is not
capable of handling the output wattage may lead to permanent
damage.
NOTE: Stewart Audio will not be held responsible for
damage to your CVA50-1 Priority PA amplier or connect-
ed equipment if the instructions in this manual are not
followed.
NOTE: For additional operating precautions, please refer
to “Important Safety Instructions” located on Page 2.

16
3.2 Controls, Indicators, and Connectors
CVA50-1 PA
1
1235 6 7
4
1
Speaker Out Connector
2
Power Connector
3
Clip Indicator LED
5
Power Indicator LED
6
Remote Volume Control
8
3.5mm Input #2
4
Signal Present Indicator LED
9
Ducking Sensitivity Knob
98
10
10
11
11
10
10
Local Input Level Knob
11
11
25V Paging Input
12
12
Mic / Line Input
12
12
13
13
14
14
7
RCA Input #1
13
13
Paging Input Level Knob
14
14
Mic Gain Hi / Low Switch
17
3.2.1 Indicators
The CVA50-1 Priority PA ampliers have three rear panel LEDs to indi-
cate the status of the amplier. The blue LED, labeled “ON”, will be lit
when the unit is not in sleep mode. The green LED, labeled “SIG”, will
light when an audio signal is present on the audio input. When the unit
is operating with both green and blue LEDs lit and the audio input sig-
nal goes away or is removed, the green “SIG” LED will go out and the
unit will continue to operate with the blue LED on for approximately 5
minutes before going into sleep mode. When signal is present and out-
put is going to the speakers the red LED, labeled “Clip”, will light when
the input signal is too hot. The “LEVEL” control must be adjusted until
the CLIP LED goes out for undistorted sound amplication.
3.2.2 Controls
The CVA50-1 Priority PA controls are located on the rear of the unit.
There is no power switch so the amplier will power up into a sleep
state when power is rst applied. The CVA50-1 Priority PA Signal
Sense Technology (SST™) will power up the amplier from sleep
when a signal is detected. After 5 minutes without an input signal the
amplier will go into sleep mode.
The rear panel contains two volume knobs. The amplier is set to run
off of a line-level source and the level should be adjusted for optimum
performance. To adjust this knob, you will need a small at-head
screwdriver. While a typical program source level is present, spin the
rotary knob as far clockwise as you can without hearing distortion or
without the “Clip” indicator illuminating. If the signal is distorting and
the knob is all the way counter-clockwise, adjust the gain down at the
source level.
The “Mic Gain” setting will adjust for the sensitivity of the microphone
by different manufactures beyond what the volume control offers. If
the microphone is generally too loud, select the “High” setting by slid-
ing the switch to the right. If the microphone is generally too quiet, se-
lect the “Low” setting by sliding the switch left.

18
3.2.3 Remote Volume Control
CVA50-1 Priority PA ampliers can have their volume remotely con-
trolled (or muted) via the Euro Block input on the rear of the amplier.
The remote volume control allows the units volume to be controlled
through the use of an external potentiometer which can be located
wherever convenient for the user. Remote muting is also useful for re
-alarm situations in which all unnecessary sound must be silenced.
NOTE: If the remote volume control connector is utilized,
it will override the volume knob on the rear of the unit.
In order to remotely control the volume of the unit, a 10k-ohm potenti-
ometer should be placed between the +10V pin and the GND (Ground)
pin on the rear of the unit with its wiper on the RVC pin. The volume
will be determined by the selected resistance on the potentiometer,
the greater the resistance the louder the volume.
The amplier can be remotely muted by making a connection between
the GND pin and the MUTE pin. No power should be applied to these
pins, simply a contact connection.
19
3.2.4 PA Ducking
The CVA50-1 Priority PA includes a ducking feature which allows the
PA channel to talk over the other channels. When a 25V Signal is de-
tected on PA line, it will lower the other channels by a set amount.
Both the sound threshold to activate the ducking (Ducking Sensitivity)
and the amount the other channels are lowered (Ducking) are congu-
rable via recessed knobs on the front panel.

20
4 Troubleshooting
Problem: Power indicator does not turn on.
Procedure: Check that the amplier is plugged into a live outlet. After
you have ensured that it is not a power issue, disconnect any speakers.
If the amplier turns on after a few seconds delay, then the problem is
in the output connection. Check wiring and speakers for short circuits.
Problem: No output on one or both channels; Power indicator is
lit.
Procedure: Check that level controls are not turned down. Check that
input and output connections are secure. Refer to section 2.5 to en-
sure that you have properly connected your speakers. Ensure signal
present LED is ashing to denote a signal. If there is no signal detected
check signal source and that level controls are set high enough.
Problem: Microphone level is too low even after adjusting level
knob
Procedure: Refer to section 3.2.2 to adjust the gain switch on the rear
of the amplier.
Problem: Channels 2-4 cut out while speaking into the microphone
Procedure: This is part of an intended feature calling ducking. Refer to
section 3.2.4 to adjust this to a more acceptable level.
Problem: Amplier overheats and/or shuts off.
Procedure: Review section 2.3 on proper cooling procedures. Check
the signal lights on the front of the amplier to see if the signal is over-
driving (the Clip light ashes red frequently). Overdriving the amplier
for extended periods of time can cause a thermal shutdown.
21
4 Troubleshooting (Cont.)
Problem: Output sound is distorted or cracking.
Procedure: Check all cables for damage or loose connections and re-
duce the gain on the input signal at the mixer or preamp level. Replace
the cables and loudspeakers temporarily to see if this resolves the
problem. If problem still exists, contact your Authorized Dealer for ser-
vice.

22
5 Technical Specications
Maximum Output 30Hz - 20kHz
CVA50-1 Priority PA 50W @ 70V
Frequency Response (+0, -3 dB) 100Hz—20kHz
Power Bandwidth +/- 3dB 80Hz-30kHz
THD+N <0.1%
Signal-to-Noise Ratio >80dB
Remote Volume Control 0-10V DC, 4-pin Block
Input Sensitivity .5V (-3 dBV)
Standard Voltage Gain 151X (43dB) @ 70.7V
Input Impedance (Balance/Unbalanced) 20k Ohms/10k Ohms
Sleep, Idle Current Draw, 1/8 Draw 0.005 / 0.01 / 0.15 Amps
Class D
Input Connectors Mic (3-pin Euro Block),
RCA, 3-pin Euro Block,
25V 2-pin Euro Block
Output Connectors Euro Block 2-pin
Power Supply External In-Line 48DVC
Cooling Convection-Cooling
Controls Level
LED Indicators Power, Signal, Clip
Construction Aluminum Chassis
Plenum Rating UL 2043 Approved
Dimensions
Height 1.38in (3.5cm)
Width 6.25in (15.9cm)
Depth 4.13in (10.5cm)
Weight 1.2 lbs (0.54kg)
Stewart Audio reserves the rate to change features and specications without notice.
23
6 Warranty Information
6.1 Warranty Summary
All Stewart Audio ampliers and accessories, unless excluded in this
summary, are covered by a 3-year limited warranty on parts and labor
from the data of purchase. In order to be eligible for warranty repairs,
the ampliers and accessories must have been purchased through an
authorized Stewart Audio dealer and submitted by the original purchas-
er. This warranty is only valid in the country in which the amplier was
purchased.
6.1.1 Eligibility Requirements.
Stewart Audio warrants against all malfunctions which come as a result
of component or manufacturer defect. The amplier is also covered
from all failures which arise during the warranty period (3 years from
date of purchase) that are not a result of misuse. The following actions
will void your warranty:
 The power cord or AC plug has been damaged through misuse.
 The amplier has been exposed to moisture or extreme tempera-
tures.
 The amplier has been dropped, items have been dropped on the
amplier, or the enclosure has been damaged.
 The amplier has been opened by the operator.
 The amplier was improperly packaged when sending to the fac-
tory for repair, resulting in damage.
 Any of the precautions or instructions found in this manual were
not followed.
Damages resulting to the amplier which are not covered under this
warranty can be factory-repaired at cost to the customer. Use the con-
tact information below to initiate the repair process.
6.2 Return Procedure
This section includes the return procedures which must be followed in
order to prevent processing delay or cost to the customer. Please read
the entire section before contacting Stewart Audio for returns.

24
6.2.1 Return Authorization Number
All returns to the factory for service must be accompanied by a Return
Authorization (RA) number. One can be obtained by contacting Stewart
Audio at [phone] or via e-mail at sup[email protected].
NOTE: Any defective products received without an RA number will
be returned to sender at their expense.
If Stewart Audio is unable to contact the sender in 14 days, the mer-
chandise will be considered scrap and may be disposed of.
6.2.2 Shipment Instructions
If Stewart Audio requests that you ship the defective product back to
their service center, please refer to the guide below. To ensure prompt
warranty service, be sure to follow all instructions.
1. Return Authorization (RA) is required for product being sent to the
factory for service.
2. See packing instructions in section 6.2.3.
3. Ship the defective product using a method which provides for or-
der tracking or order conrmation. The service center is located at
the following address:
Stewart Audio
14397 Cuesta Court Suite D1
Sonora, CA 95370
4. Use a bold black marker and write the RA number on three sides
of the box.
5. Record the RMA number for future reference. The RA number can
be used to check the repair status.
6.2.3 Packaging Instructions
Should Stewart Audio request that you ship your product to their ser-
vice center, these instructions must be followed in order to ensure safe
delivery. If they are not followed, Stewart Audio assumes no responsi-
bility for damaged goods and/or accessories that are sent with your
unit.
25
6.2.3 Packaging Instructions (cont.)
1. Please write the RA number on three sides of the box. Include the
Stewart Audio RA number inside the box and a brief description of
the problem.
2. Do not ship any accessories (manuals, cords, hardware, etc.) with
your unit. These items are not needed to service your product.
Stewart Audio will not be held responsible for these items if they
are returned with the ampliers.
3. When shipping your amplier, it is important that it has adequate
protection. We recommend you use the original packing material
when returning the product for repair. If you do not have the origi-
nal box, see number 4.
4. If you provide your own shipping pack, the minimum recommend-
ed requirements for materials are as follows:
a. 275 P.S.I. burst test, Double-Wall carton that allows for 2-
inch solid Styrofoam on all six sides of unit or 3 inches of
plastic bubble wrap on all six sides of unit.
b. Securely seal the package with an adequate carton sealing
tape.
c. Do not use light boxes or “peanuts”.
NOTE: Damage caused by poor packaging will not be covered un-
der warranty.
6.2.4 Estimate Approval
An estimate for all non-warranty repairs will be provided to the custom-
er once the unit has been shipped to the factory. The customer is re-
sponsible to approve this estimate within 7 days. If the repairs are not
approved within 14 days, Stewart Audio reserves the right to consider
the unit scrap and may discard it.
6.2.5 Payment of Non-Warranty Repairs
Payment for non-warranty repairs must be submitted to Stewart Audio
before the product will be returned to the customer.

26
7 Accessories
The following accessories are available from Stewart Audio for your
amplier.
All part numbers shown are Stewart Audio Part Numbers.
To purchase these accessories or to see the full
Stewart Audio product lineup, visit us at:
www.stewartaudio.com
Mounting Brackets
AV-POLE Pole-mount bracket for AV Series ampliers
AV-BRACKET Universal mounting bracket for AV Series ampliers
Connection Adapters
ADPT-RCA Mono Female RCA to male Euroblock.
ADPT-SUMRCA Stereo Female RCA to male Euroblock.
ADPT-SUM35 Stereo Female 3.5mm to male Euroblock
WP-RVC-B Wallplate with 10k potentiometer and knob for re-
mote volume control (Black)
WP-RVC-A Wallplate with 10k potentiometer and knob for re-
mote volume control (Aluminum)
Wall Plates
27
8 Notes
For Your Record
In the spaces provided below, record the model and serial
number located at the rear of your amplier.
Retain this information for future reference.
Model No. ________________________________________
Serial No. _________________________________________
Purchase Date _____________________________________